304 probi,e:m of the origin of species. 



pleasing, but what conditions or determines growth, nutrition, sensibility, 

 movement, and reproduction in these ultimate units? In higher units we 

 must ascribe the existence of these same attributes to the "necessary condi- 

 tion" that we "can only" explain evolution by supposing the existence of such 

 units. There simply results this state of things : Either we must assume that 

 the fundamental attributes of organism are one thing in an organism and 

 another in the ultimate vital units, or we must, to be logical, go on creating 

 cycles of ultimate units one within the other ad infinitum. In any event, we 

 always arrive at exactly the same point. How shall we connect in any logical 

 way these vital units with the chemico-physical phenomxCna, which must 

 ultimately form the basis of the interpretation of organic phenomena ? 

 Weismann says of these units : 



As to their size, we can only say that they are far below the limits of visibility, and 

 that even the minutest granules, which we can barely perceive by means of our most 

 powerful microscopes, can not be small individual biophores, but must be aggregates 

 of these. On the other hand, the biophores must be larger than any chemical molecule, 

 because they themselves consist of a group of molecules among which are some of com- 

 plex composition, and therefore of relatively considerable size. 



And De Vries says: 



The pangenes are invisibly small ... all the various kinds of pangenes occur in 

 the nucleus. 



We must accept Weismann's dictum that the biophore is larger than any 

 "organic molecule," but he evidently forgets that some of the organic mole- 

 cules approach dangerously near the limits of visibility. The determinants, 

 very numerous in all animals, and reaching in Arthropods "hundreds of 

 thousands," are not in multicellular animals "single biophores," but the 

 determinant "is a group of biophores w^hich are bound together by internal 

 forces to form a higher vital unit." "On this basis the germ plasm repre- 

 sented by the chromatin of the egg nucleus of an insect egg must contain 

 'hundreds of thousands' of these determinants, each made up of biophores, 

 each in turn larger than any organic molecule." Now we know with 

 considerable accuracy the size of many organic molecules, and if there be 

 biophores endowed as Weismann supposes, each vital unit must be con- 

 stituted of enough organic molecules to carry on the "fundamental char- 

 acters." When this is further followed out the whole idea becomes an all 

 too obvious absurdity, because the amiount of the chromatin in the germ 

 cells of Leptinotarsa is far too small to contain the amount of organic mole- 

 cules that it must according to Weismann's hypothesis. By measuring dur- 

 ing the oogonial and spermatogonial divisions the diameter and length of the 

 chromosomes, I have come to the conclusion that the maximum amount of 

 chromatin in the oogonia or spermatogonia is not over 0.0000225 c. mm. 

 If we suppose each biophore to be made up of only five molecules (an 

 unthinkable supposition), and each determinant of only two biophores and 



